Kothari 2000.

Study characteristics
Methods	Study design: randomized controlled trial Study grouping: 2 groups, monoprophylaxis
Participants	Baseline characteristics Ondansetron Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): NA Received treatment (n): NA Analysed (n): 50 Age (mean ± SD, median (IQR), median (range)): 47.9 Weight (mean ± SD, median (IQR), median (range)): 87.5 BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): 22/24/4/0 Gender (female in %): 72 Non‐smoker (%): NA History of PONV/motion sickness (%): NA/24 Type of general anaesthesia: inhalational anaesthesia (sevoflurane) Duration of anaesthesia or surgery (in min; as mean or median): 65.1 Use of perioperative opioids (if yes, which?): NA Type of surgery: laparoscopic cholecystectomy Dimenhydrinate Assessed for eligibility (n): ‐ Enrolled (n): ‐ Randomized (n): NA Received treatment (n): NA Analysed (n): 58 Age (mean ± SD, median (IQR), median (range)): 49.7 Weight (mean ± SD, median (IQR), median (range)): 85.1 BMI (mean ± SD, median (IQR), median (range)): NA ASA I/II/III/IV (n): 25/27/6/0 Gender (female in %): 74.14 Non‐smoker (%): NA History of PONV/motion sickness (%): NA/22.41 Type of general anaesthesia: inhalational anaesthesia (sevoflurane) Duration of anaesthesia or surgery (in min; as mean or median): 61.1 Use of perioperative opioids (if yes, which?): NA Type of surgery: laparoscopic cholecystectomy Included criteria: ASA I to III, undergoing elective laparoscopic cholecystectomy Excluded criteria: NA Pretreatment: baseline characteristics (age, weight, ASA): no. Potential effect modifiers (gender, duration of anaesthesia, history of motion sickness): no; (history of PONV, non‐smoker, perioperative opioids): unclear
Interventions	Intervention characteristics Ondansetron Dose: 4 mg Time point of administration: before induction of anaesthesia Route of administration: IV Rescue antiemetics (if yes, which?): 34% (patients given their choice of antiemetic at the discretion of the anaesthesiologist) Dimenhydrinate Dose: 50 mg Time point of administration: before induction of anaesthesia Route of administration: IV Rescue antiemetics (if yes, which?): 29% (patients given their choice of antiemetic at the discretion of the anaesthesiologist)
Outcomes	Vomiting (0 to 24 hours) Outcome type: dichotomous outcome Nausea (0 to 24 hours) Outcome type: dichotomous outcome Subjects with any AE (0 to 24 hours) Outcome type: dichotomous outcome Headache (0 to 24 hours) Outcome type: dichotomous outcome Sedation/drowsiness (0 to 24 hours) Outcome type: dichotomous outcome Adverse events (general notes in the publication, 24 hours' observation) Outcome type: general notes on side effects
Identification	Sponsorship source: NA Country: USA Setting: inpatient, single‐centre Author's name: W.C. Boyd Institution: Departments of Surgery and Anesthesiology, Gundersen Lutheran, La Crosse, WI 54601, USA Email: AN Address: Departments of Surgery and Anesthesiology, Gundersen Lutheran, 1836 South Avenue, La Crosse, WI 54601, USA Duration of study: 1 November 1998 to 1 June 1999 Language: English Study's primary outcome: NA Trial registry number: NA
Notes	None
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Judgement comment: quote: "randomization was performed using a computer‐generated randomized list''
Allocation concealment (selection bias)	Unclear risk	Judgement comment: no statement
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Judgement comment: insufficient information on blinding ("double‐blind")
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Judgement comment: quote: "nurses blinded to which antiemetic the patients had received recorded all episodes of nausea, vomiting, and retching in the recovery room by direct questioning, spontaneous complaint of the patient, or side effects''
Incomplete outcome data (attrition bias) All outcomes	Low risk	Judgement comment: quote: "of the 20 patient excluded, 15 had received an additional antiemetic preoperatively 4 were converted to open cholecystectomy, and the case of 1 was aborted because of the intraoperative finding of carcinomatosis. Of the 108 remaining patients available for analysis, 50 [of] whom were randomized to receive ondansetron (group 1) and 58 to receive dimenhydrinate (group 2)''
Selective reporting (reporting bias)	Unclear risk	Judgement comment: no reference to a study protocol or trial registry number reported
Other bias	Unclear risk	Judgement comment: quote: "patient demographics were similar in both treatment groups" Baseline characteristics (age, weight, ASA): no. Potential effect modifiers (gender, duration of anaesthesia, history of motion sickness): no; (history of PONV, non‐smoker, perioperative opioids): unclear